Lesson 4: Radio (Teacher Notes)

This is the teacher guide for Lesson 4.
It includes lesson flow, strategies, and example code.

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Learning Objectives

• Students understand how the Micro:bit sends and receives wireless radio messages.
• Students can set a radio group/channel.
• Students can send numbers or strings to another Micro:bit.
• Students can receive and act on incoming messages.

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Suggested Lesson Flow

1. Introduction (5 mins)

• Ask: “How do walkie-talkies communicate?” → introduce the idea of radio signals.
• Explain that Micro:bits can send messages wirelessly if they are on the same group number.

2. Demonstration (5 mins)

Show how to:

• Set the radio group in on start
• Send a number with a button press
• Receive a number and display it

Emphasize:

• Devices must be on the same group to communicate.
• Pressing a button sends the message.

3. Student Activity (15–20 mins)

Students build:

• Button A → sends 1
• Button B → sends 2
• On receive → show the received number

Then test with a partner or group.

Optional challenges:

• Send a word or name.
• Create a score system.
• Add sounds or icons.
• Apply message filtering (e.g., only show messages that equal 5).

4. Wrap-Up (5 mins)

Ask reflective questions:

• “Where is wireless communication used in real life?”
• “What happens if different groups overlap?”
• “How could we combine variables + radio for a multiplayer game?”

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Common Issues & Fixes

Problem	Solution
Micro:bits aren’t communicating	Check both devices use the same radio group number.
Nothing shows on the screen	Ensure show number is added inside the received event block.
Messages interfere with other groups	Assign different group numbers per pair or table.

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Demo Code Example (JavaScript)

```javascript radio.setGroup(1)

input.onButtonPressed(Button.A, function () { radio.sendNumber(1) })

input.onButtonPressed(Button.B, function () { radio.sendNumber(2) })

radio.onReceivedNumber(function (receivedNumber) { basic.showNumber(receivedNumber) })